1. Field of the Invention
The present invention relates to an air conditioner system with a control for ensuring optimum refrigerant temperature at all times, and, more particularly, to a multi-unit type air conditioner system having a heat-pump type refrigeration cycle, which employs a single outdoor unit to control a plurality of indoor units.
2. Description of the Related Art
Conventionally, the above-mentioned multi-unit type air conditioner system operates one or two compressors of a single outdoor unit, using a single distributing unit, in accordance with a demand-capability based on the air-conditioning load of each indoor unit
However, in a case where super heat of refrigerant is high (such as when the air-conditioning load of the individual indoor units is high) a multi-unit type air conditioner system having the above conventional structure cannot prevent the refrigerant expelling temperature at one or two compressors from rising to a level significantly higher than that at which it would be under normal operating conditions, with the result that a rapid deterioration of the refrigerant in each compressor in the air conditioner system is likely to occur, in turn, leading to carbonation of the lubricating oil and the seizure moving parts within each compressor, such as pistons and control rods. Further, when the refrigerant suction temperature of each compressor of this type of air conditioner system is high, the temperature of winding of a motor of each compressor is likely to increase above the rated operative range, with the result that in the electric insulation characteristic.
The above shortcomings of the conventional air conditioner system hinder its safe operation.
One such air conditioner system as described above is a super multi-unit type air conditioner system which has an outdoor unit coupled to a plurality of branching units which are in turn coupled to respective indoor units.
According to this type of conventional super multi-unit type air conditioner system, however, discrimination of demand-capability is made only on the basis of the capability (also called horse power) of each indoor unit, without any consideration on pressure loss in a refrigerant pipe connecting each branching unit and its associated indoor unit, although the length, and the height, of this pipe varies depending on its installing environment or condition. It is therefore difficult to provide the optimum refrigerant flow rate control for the demand-capability of each indoor unit. For instance, with a long output frequency pipe in use, the air conditioner system will run in a super heating cycle, so that its safe operation will be hindered.